1. Field of the Invention
The present invention relates to a charging member for use in an electrophotographic apparatus, and a process cartridge and an electrophotographic apparatus using the charging member.
2. Description of the Related Art
An electrophotographic apparatus using electrophotography mainly includes an electrophotographic photosensitive member, a charging apparatus, an exposure apparatus, a developing apparatus, a transfer apparatus and a fixing apparatus. For the charging apparatus, contact charging apparatuses are often used which apply voltage to the charging member disposed in contact with or in the vicinity of the surface of the electrophotographic photosensitive member. Here, only DC voltage, or voltage of DC voltage superimposed with AC voltage is applied to the charging member.
For more stable charging of the electrophotographic photosensitive member by contact charging, Japanese Patent Application Laid-Open No. 2003-316112 proposes a charging member for contact charging including a surface layer having a protrusion derived from a resin particle or the like in the surface.
On the other hand, a contact charging apparatus in which DC voltage is applied to a charging member with being superimposed with AC voltage may cause vibration noise generated by resonance of an electrophotographic photosensitive member with the charging member due to charges generated on the surfaces of the electrophotographic photosensitive member and the charging member. For dealing with such a problem, Japanese Patent Application Laid-Open No. 2008-158437 proposes use of a hollow spherical inelastic particle as a resin particle that roughens a surface layer of a charging member, to thereby enhance vibration resistance, and sound insulation and sound absorption effects.